EP3245701A1

EP3245701A1 - Method for optimizing consumption of reactive power

Info

Publication number: EP3245701A1
Application number: EP15805599.6A
Authority: EP
Inventors: Zheng Hu
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-11-19
Filing date: 2015-11-19
Publication date: 2017-11-22
Also published as: US10707682B2; US20170331288A1; JP6879912B2; JP2017535239A; WO2016079435A1; CN107112756A; FR3028681A1; FR3028681B1

Abstract

The invention relates to a method for optimizing consumption of reactive power in an electrical network including a system for monitoring and adjusting electrical power supply, said system comprising an electrical generator, electrical loads, a power compensation system, an electric transmission line, an electro-digital processor and a remote-readable meter. The method comprises the steps consisting in: measuring the dataset of the electrical loads via at least one remote-readable meter; collecting the dataset of the electrical loads and transmitting it to the electro-digital processor in order to establish data curves; calculating a power factor of the electrical loads; enabling reactive power compensation by setting the type and configuration of the compensation systems to be installed, when the calculated power factor has a value lower than or equal to a predefined threshold value; and compensating for reactive power by actuating the installed compensation systems.

Description

METHOD FOR OPTIMIZING THE CONSUMPTION OF REACTIVE ENERGY

Field of the invention

The present invention relates to the field of monitoring electrical networks and optimizing the consumption of reactive energy.

It relates more particularly to a method for automating the detection of reactive energy and thus allow the optimization of energy consumption implemented in power grids.

State of the art

In the state of the art, a solution described in patent application FR2494055 is known. This application describes a device for compensation of reactive electrical energy in a network comprising at least one compensation unit connected to the network. The compensation unit comprises an inductor, a capacitor and a first bidirectional thyristor switch, and a second directional thyristor switch, and control means comprising a logic gate "or", connected in input on the one hand to a first measurement circuit with detection of a predetermined threshold of the voltage across said first switch and secondly with a second measuring circuit with detection of a predetermined threshold of the voltage across said second switch.

The solution proposed by the patent application FR2693601 describes a reactive power compensation device, which comprises means for measuring the current in the main power supply circuit, downstream of the connection of the controlled switch, and measuring means of a magnitude representative of the apparent power, connected to the output of the current measuring means. The opening of the controlled switch is controlled when said representative magnitude exceeds a predetermined threshold value.

Current regulation solutions for a reactive energy compensation system are also known in the state of the art.

Patent application FR2873866 describes an example of a current regulation device. The device in question comprises a coupling transformer whose secondary winding is intended to be connected in series between an electrical energy distribution network and a reactive energy compensation capacitor, an active filter comprising an inverter, and a loop IEC 60050 - International Electrotechnical Vocabulary - Details for IEV number 841-21-31-2 Electricity supply / Electro-magnetic equipment / Instruments and apparatus / Devices / Description of the invention: Current control system estimating a fundamental value of electric current, in order to control the inverter of the active filter.

Disadvantages of the prior art

Solutions of the prior art relating to devices for compensation of electrical energy reactive in a network have several disadvantages.

Some of the solutions are based on the predetermined machine thresholds, which do not have the possibility of remote detection of the reactive energy and therefore do not allow to adapt to real situations of use.

Other solutions require the intervention of workers on site at given times. This solution does not allow remote monitoring and permanent optimization.

Moreover, the solutions of the prior art are suitable for the compensation of the individual electrical charge. It does not allow centralized management of multiple sites at the same time.

Finally, the solutions of the prior art are limited to passive compensation. The compensation devices must wait for the triggering of the predetermined threshold to start the compensation. They do not offer the possibility of preprogrammed active compensation.

Solution provided by the invention

In order to remedy these drawbacks, the invention relates, in its most general sense, to a method for optimizing the consumption of reactive energy in an electrical network by a monitoring and adjustment system, said system comprising an electricity generator, electric charges, an electricity meter, a power compensation system, a power line, and an electro-digital processor. The method comprises the steps of measuring the powers consumed by the electric charges by at least one electric meter having remote readings, collecting all of these data and transmitting them to the electro-digital processor for establishing curves of data, to calculate the power factor of the electrical charges, to identify the need to compensate the reactive energy when the calculated power factor has a value less than or equal to a predefined threshold value, to determine the type and configuration of compensation to install and then control said compensation system. Preferably, the measurement of the electric charge data set, the data collection, the power factor calculation and the energy compensation are automated.

According to a particular embodiment, the measurement of the data set of the electrical charges, the collection of data, the calculation of the power factor and the energy compensation are controlled in real time and in distance.

According to another embodiment, the steps in the method can switch between a periodic measurement mode and a random measurement mode over time. According to another particular embodiment, the energy compensation is actively performed by a preprogramming of the parameters.

Advantageously, two types of compensation can be achieved depending on the objectives to be achieved. Thus, it may be compensation called "compensation referred to electric charges" and a compensation called "compensation referred to the power grid." "Compensation referred to electric loads" is understood to mean compensation made when the power factor at the level of the electrical loads crosses a determined threshold (threshold advantageously by the end users of the loads), and by "compensation referred to the electrical network", a compensation achieved when the power factor at the level of the electricity network crosses a determined threshold (threshold advantageously determined by the operators of the network).

According to one embodiment, the compensation referred to electric charges is achieved by a compensation of the reactive energy in a compensation mode selected from one of the following three modes: an individual compensation mode, a local compensation mode and a mode of compensation. global compensation.

According to another embodiment, the compensation referred to the electrical network comprises a data collection step, which is calculated, automatically raised in passive mode and a logical compensation step, which is a distribution plan of the compensation referred to loads.

This invention has several advantages, from the technical point of view, a better adaptation of the dimensioning, the decreases of the drops of tension and the losses in line. From an economic point of view, the elimination of reactive energy consumption and the increase in active power reduce the company's bill.

In addition, this invention makes it possible to carry out a remote energy diagnosis and more particularly to avoid the sending of technicians on site and the installation of expensive apparatus for the measurement. It's a tailor-made service.

Detailed description of the figures

The present invention will be better understood on reading the description which follows, relating to nonlimiting examples of embodiment, and referring to the appended drawings in which:

FIG. 1 represents a schematic diagram according to the invention illustrating a monitoring and regulation system in an electricity network;

FIG. 2 represents the vectors of the apparent, active and reactive portions of the current and of the power;

FIG. 3 represents the active power, the reactive power and the apparent power in the three-phase AC circuits;

FIG. 4 represents the power factors of the three phases collected every second for a duration of 90 seconds.

FIG. 5 represents a schematic diagram illustrating the flow of data collected between the compensation referred to the electrical charges and the compensation targeted to the electrical network.

Detailed description of non-limiting examples of the invention

FIG. 1 represents a schematic diagram according to the invention illustrating a power supply monitoring and control system 100. The monitoring system comprises an electricity generator 110, electric charges 120, a reactive power compensation system 130 , an electricity transmission line 140, an electro-digital processor 150 and an electric meter having the remote readings 160. The electricity generator 110 supplies power to the electrical charges 120 via the power line 140. In the AC circuits, a transformer delivers a current at a certain fixed voltage. Depending on the characteristics of the electrical charges 120, they can be classified as resistive receivers, inductive receivers and capacitive receivers. Inductive receivers and capacitive receivers induce phase shifts of the current with respect to the voltage. This phase shift causes unnecessary consumption of electrical energy, which does not correspond to heat or mechanical work. In order to save energy, the power compensation system 130 is set up and configured by the digital processor 150.

Electrical meters (160) have remote readings and measure the power consumed by the electrical charges according to the user need, either punctually in a predetermined time, or automatically continuously. The electric meters are located either on the side of the electrical charges, or on the side of the electricity generator, or located as an intermediate. The electric meters transfer power data consumed by the electrical charges to the digital processor 150, where the data is analyzed by means of the algorithm which makes it possible to determine the configuration to be applied to the controller of the power compensation system 130.

Figure 2 shows the phase shift of the current and the active and reactive power. Electrical charges include inductive, capacitive and resistive receivers, which can induce phase shift. When an inductive / capacitive receiver is connected in the circuit, the total current Is will be out of phase with phi (φ) with respect to the voltage and broken down into two parts: the active current Ip = Is x cos <p, where the component is in phase with the voltage, and the reactive current Iq = Is x sirup, where the component is phase shifted by 90 ° of the voltage. The active power formula:

P = U x Is x cos <

φ is the phase shift of the total current with respect to the voltage, and the factor cos <p is called the power factor, which is often indicated on the wafer of most electrical machines. The reactive power Q is defined by analogy with the active power P:

Q = U x Is xsincp

Reactive power makes it possible to evaluate the importance of inductive receivers (motors, fluorescent lamps,) and capacitive receivers (capacitors) in the installation. The product of the voltage by the total current is called the apparent power S:

S = U x Is

Figure 3 shows active power, reactive power, and apparent power in three-phase AC circuits. This data is collected every second for a period of 90 seconds.

The electric charges, powered by alternating current, involve active and reactive energies, which correspond to work respectively under active and reactive powers for a certain duration. Active energy is transformed into mechanical energy or heat. The reactive energy is mainly due to the inductive / capacitive receivers present in the loads and does not correspond to heat or mechanical work. In a known manner, the reactive energy can be reduced by connecting the compensation system on the power transmission line, for example a capacitor battery system. The compensation system can also incorporate an anti-harmonic filter, which aims to reduce harmonic distortion and to avoid peaks causing over-consumption and affecting the service life of equipment.

Figure 4 shows the power factors of the three phases collected each second for a duration of 90 seconds. The power factor cos φ on a value of 0.75 is below the predefined threshold value, which indicates an excessive reactive energy demand of the equipment of the installation. The purpose of the compensation is to maximize the power factor without inducing overcompensation / overload. For example, when the power factor is below 0.95, it triggers a high phase shift e-mail alert. In addition, when compensation becomes unnecessary, another alert is sent.

The method for optimizing energy consumption has four steps.

The first step is to measure, during a period of monitoring, the powers consumed by electric charges. The measurement is carried out automatically continuously for a given period of time or up to a predefined quantity of energy consumed. For example, from remote readings of new generation electricity meters, data is collected every 10 minutes. In a factory where workers work from 8:00 am to 2:00 am, recording power loads for a week will show typical consumption behaviors, such as changes in the parameters at the time of connection of each machine. When the reactive energy consumption exceeds a certain threshold before the end of the week, then indicating a waste of energy, the monitoring period ends earlier.

The second step consists in transmitting the data to the electro-digital processor 150 which analyzes the type of phase shift (advance or delay), the phase shift moment and the phase shift duration. In known manner, the phase of the capacitive current is in advance of 90 ° with respect to the phase of the voltage while the phase of the inductive current is delayed by 90 °. Resistive receivers do not change the phase of the current.

The third step is a diagnostic step in which the compensation algorithm calculates the power factor and triggers, if necessary, an alert, in particular according to the contract linking the electricity supplier and the user who has the loads. electric. An example is the one shown in Figure 4: the recommended value of the power factor cos φ located in the range (0.95, 1) is considered as the optimized situation. Outside this range, the compensation system is activated either under manual control or automatically. In order to ensure the stability of the compensation system, the duration of the power factor outside this range is also considered.

The fourth step is to install the compensation equipment according to a compensation method adapted to the network concerned and to the needs thereof. The compensation can thus be carried out according to three modes.

The first mode consists of an individual compensation: the compensation devices are connected directly to the terminals of each inductive / capacitive receiver. This compensation is technically ideal since it produces the reactive energy at the place where it is consumed, and in a quantity adjusted to the demand. However, this compensation is preferably used for the machine whose operating hours reach certain times and / or the reactive energy reaches a certain threshold.

The second mode consists of local compensation: compensation equipment is installed per sector. In one sector, several machines with different receivers are connected to the same power supply network. The load curve of the powers of a sector has reactive powers and reactive energies as a result of the cancellation and the amplification of the phase shift of the different machines connected in this sector.

The third mode consists of global compensation: the compensation equipment is installed at the head of the electrical loads and provides all the charges for the compensation. They help relieve the transformer installed by the electricity supplier. However the phase shift can vary randomly due to the collective effect of all connected machines. All stages are automated and can be controlled in real time and remotely. Depending on the consumption history, the parameters can be programmed upstream to actively compensate for the use of electrical loads. According to the user's requirement, the parameters may be different at the requested time, such that the range of the power factor cos φ may be changed remotely so as to present, for example, a different value of the afternoon with the morning one and respectively.

Due to the periodicity of some machines, the periodic measurement mode may mask some information. Switching from a periodic measurement mode to a random measurement mode helps to verify certain information. Also, and advantageously, when the operation of measuring the power of the load is in random mode, all the other operations switch to random mode.

The compensation is made according to the objectives to be achieved. In general, there are two categories of objectives to be attained: that with respect to electrical charges and that with respect to the electricity grid. The compensation referred to the electrical charges is a compensation performed when the power factor at the level of the electrical charges exceeds a certain threshold determined by the end users of the charges, whereas the compensation referred to the electrical network is a compensation made when the power factor at the level of the electricity network exceeds a certain threshold determined by the operators of the network.

The examples above are for offsetting expenses for end-customers, including small and medium-sized businesses, or communities. The collected data are raw data concerning the consumption of the reactive energy of the electric charges. And the compensation is done by remote control of the compensation device, for example a capacitor bank.

The following paragraphs describe the compensation in the power grid. The problem of the state of the art is that normally it is done in the direction Top-Bottom. The document "Achieving Reactive Power Compensation in the Distribution Transformer Monitoring System" presented at the International Conference on Electricity Distribution (C1CED) 2012, presents the realization of a device for network-based compensation based on on a distributed transformer system.

However, it is only a global compensation based on global consumption data, no method of the prior art integrates the possibility of compensation through the control and control of the compensation of a set of SME-SMI users or communities.

Our proposal is to propose a compensation method referred to the network based on a distribution system. Due to the charge compensation, the individual compensation data is obtained for the loads of each SME-SMI user. And with these data, compensation can be made with respect to the public electricity grid by piloting each user. With actuator sensors directed from a cloud-based technical platform, it is possible to control the reactive energy consumption of end-users. It is also possible to operate according to the own constraints of the distribution network that it is public or that it concerns a network of different users.

In order to achieve the compensation referred to the network, two aspects are developed respectively in the fields of data collection and compensation. In the compensation covered by the charges, the data collection is carried out by remote reading in active mode with raw data, whereas in the compensation referred to the network, the data collection is a passive mode measure, with all the data already available. calculated, automatically reported. Moreover, in the compensation referred to loads, the compensation is physical by devices like a battery, while the compensation referred to the network is logical, which is presented as a plan of distribution of the compensation referred to charges to provide a benefit to the entire power grid.

The compensation is based on a two-level technical infrastructure:

• ^1st level,

a platform comprising an aggregation engine, a search engine and a calculation engine in the cloud in order to:

-determine whether a user is eligible for reactive energy compensation,

-supervise the reactive energy,

-to allow electricity operators like EDF to use the data model for their Big Data operating platforms.

• ^2nd level,

actuators, wireless (Internet of Things), installed in addition to the hardware part of the compensation of reactive energy and controlled by the platform.

FIG. 5 represents a schematic diagram illustrating the flow of data collected between the compensation referred to the electrical charges and the compensation targeted to the electrical network. The offsets are already carried out at the level of the loads 510 and 511. Then previously calculated data 540 are transmitted to the platform in Cloud 520. The platform in Cloud 520 transfers the computer stream for compensation referred to the network 550 to the various electricity operators 530.

This schematic compensation diagram can be understood more concretely with the example of a community, in which different loads have different compensation levels. For the community including various expenses such as the swimming pool, cable departures to the light points of public lighting, the central school canteen, each of these charges can be compensated individually according to the process of compensation referred to the charges. Moreover, thanks to the data automatically compensated, the compensation referred to the network can take place for the benefit of the public electricity grid, such as that of EDF.

In the case of a global power factor φ cos φ 0.8 achieved through the automatic feedback system with the individual compensation of loads without reaching 100% of equipment, the platform performs a plan execution for the compensation referred to the network. Thus, if we take the example of the 0.93 compensated swimming pool and the luminous points that can not be the subject of an individual compensation, the compensation referred to in the network consists in controlling the individual compensation of the pool beyond 0 , 93 for the benefit of the entire network.

The main advantage of the offsetting targeted to the public distribution network is to alleviate the constraint on the transmission system operator who must carry the reactive energy, including the end of the line as in the Var and the Alpes Maritimes. Thus, compensating reactive energy on a large scale with thousands of end-users is a credible alternative to strengthening the high-voltage electricity network in the Provence-Alpes-Côte d'Azur region, especially since the tertiary sector is largely equipped with air conditioning compressors. Air conditioning compressors are indeed likely to have a degraded power factor.

Claims

1 - Method for optimizing the consumption of reactive energy in an electricity grid by a power supply monitoring and control system (100), said system comprising an electricity generator (110), electric charges (120) a power compensation system (130), an electricity transmission line (140), an electro-digital processor (150) and a counter having the remote readings (160),

characterized in that the method comprises the steps of:

measuring power consumed by the electric charges by at least one counter having remote readings,

- collect powers consumed by the electrical charges and transmit them to the electro-digital processor for the establishment of data curves,

calculate a power factor of the electrical charges,

- allow compensation of the reactive energy by fixing the type and configuration of the compensation systems to be installed, when the calculated power factor has a value less than or equal to a predefined threshold value,

to compensate the reactive energy by an actuation of the compensation systems installed.

2 - Process for optimizing the consumption of reactive energy in an electrical network according to claim 1, characterized in that the measurement of the powers consumed by the electrical charges, the data collection, the calculation of the power factor, the configuration and The actuation of the compensation systems are automated.

3 - A method for optimizing the consumption of energy in an electrical network according to claim 1 or claim 2, characterized in that the measurement of The power consumed by the electric charges, the data collection, the power factor calculation, the configuration and the actuation of the compensation systems are controlled in real time and in distance.

4 - Process for optimizing power consumption in an electrical network according to any one of claims 1 to 3, characterized in that all the steps in the process can switch between a periodic measurement mode and a random measurement mode in time .

5 - Process for optimizing power consumption in an electrical network according to any one of claims 1 to 4, characterized in that the energy compensation is actively performed by pre-programming a range of values power factor.

6 - Process for optimizing the consumption of energy in an electrical network according to any one of claims 1 to 5, characterized in that the configuration of the compensation systems to be installed consists of defining the operating threshold of said system.

7 - Process according to any one of the preceding claims, characterized in that the compensation is performed according to two categories of objectives to achieve: the compensation referred to the electrical charges is a compensation achieved when the power factor at the loads power exceeds a certain threshold, the compensation referred to the power grid is a compensation made when the power factor at the level of the electricity network crosses a determined threshold.

8 - Process according to any one of the preceding claims, characterized in that the compensation referred to electric charges is performed by a compensation of the reactive energy according to a compensation mode selected from one of the following three modes: an individual compensation mode, a local compensation mode and a global compensation mode.

9 - Process according to any one of claims 1 to 7, characterized in that the compensation referred to the electrical network comprises a step of collecting data previously calculated and automatically reassembled in passive mode.

10 - Process according to any one of claims 1 to 7, characterized in that the compensation referred to the electrical network is logical, being a distribution plan of the compensation referred to loads.